// Copyright 2003-2010 Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland
// www.source-code.biz, www.inventec.ch/chdh
//
// This module is multi-licensed and may be used under the terms
// of any of the following licenses:
//
//  EPL, Eclipse Public License, V1.0 or later, http://www.eclipse.org/legal
//  LGPL, GNU Lesser General Public License, V2.1 or later, http://www.gnu.org/licenses/lgpl.html
//  GPL, GNU General Public License, V2 or later, http://www.gnu.org/licenses/gpl.html
//  AL, Apache License, V2.0 or later, http://www.apache.org/licenses
//  BSD, BSD License, http://www.opensource.org/licenses/bsd-license.php
//  MIT, MIT License, http://www.opensource.org/licenses/MIT
//
// Please contact the author if you need another license.
// This module is provided "as is", without warranties of any kind.
package biz.source_code.base64Coder;

/**
 * A Base64 encoder/decoder.
 *
 * <p>
 * This class is used to encode and decode data in Base64 format as described in RFC 1521.
 *
 * <p>
 * Project home page: <a href="http://www.source-code.biz/base64coder/java/">www.source-code.biz/base64coder/java</a><br>
 * Author: Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland<br>
 * Multi-licensed: EPL / LGPL / GPL / AL / BSD / MIT.
 */
public class Base64Coder {

    // The line separator string of the operating system.
    private static final String systemLineSeparator = System.getProperty(
	"line.separator");
    // Mapping table from 6-bit nibbles to Base64 characters.
    private static final char[] map1 = new char[64];

    static {
	int i = 0;
	for (char c = 'A'; c <= 'Z'; c++) map1[i++] = c;
	for (char c = 'a'; c <= 'z'; c++) map1[i++] = c;
	for (char c = '0'; c <= '9'; c++) map1[i++] = c;
	map1[i++] = '+';
	map1[i++] = '/';
    }
    // Mapping table from Base64 characters to 6-bit nibbles.
    private static final byte[] map2 = new byte[128];

    static {
	for (int i = 0; i < map2.length; i++) map2[i] = -1;
	for (int i = 0; i < 64; i++) map2[map1[i]] = (byte) i;
    }

    /**
     * Encodes a string into Base64 format.
     * No blanks or line breaks are inserted.
     * @param s  A String to be encoded.
     * @return   A String containing the Base64 encoded data.
     */
    public static String encodeString(String s) {
	return new String(encode(s.getBytes()));
    }

    /**
     * Encodes a byte array into Base 64 format and breaks the output into lines of 76 characters.
     * This method is compatible with <code>sun.misc.BASE64Encoder.encodeBuffer(byte[])</code>.
     * @param in  An array containing the data bytes to be encoded.
     * @return    A String containing the Base64 encoded data, broken into lines.
     */
    public static String encodeLines(byte[] in) {
	return encodeLines(in, 0, in.length, 76, systemLineSeparator);
    }

    /**
     * Encodes a byte array into Base 64 format and breaks the output into lines.
     * @param in            An array containing the data bytes to be encoded.
     * @param iOff          Offset of the first byte in <code>in</code> to be processed.
     * @param iLen          Number of bytes to be processed in <code>in</code>, starting at <code>iOff</code>.
     * @param lineLen       Line length for the output data. Should be a multiple of 4.
     * @param lineSeparator The line separator to be used to separate the output lines.
     * @return              A String containing the Base64 encoded data, broken into lines.
     */
    public static String encodeLines(byte[] in, int iOff, int iLen, int lineLen, String lineSeparator) {
	int blockLen = (lineLen * 3) / 4;
	if (blockLen <= 0) throw new IllegalArgumentException();
	int lines = (iLen + blockLen - 1) / blockLen;
	int bufLen = ((iLen + 2) / 3) * 4 + lines * lineSeparator.length();
	StringBuilder buf = new StringBuilder(bufLen);
	int ip = 0;
	while (ip < iLen) {
	    int l = Math.min(iLen - ip, blockLen);
	    buf.append(encode(in, iOff + ip, l));
	    buf.append(lineSeparator);
	    ip += l;
	}
	return buf.toString();
    }

    /**
     * Encodes a byte array into Base64 format.
     * No blanks or line breaks are inserted in the output.
     * @param in  An array containing the data bytes to be encoded.
     * @return    A character array containing the Base64 encoded data.
     */
    public static char[] encode(byte[] in) {
	return encode(in, 0, in.length);
    }

    /**
     * Encodes a byte array into Base64 format.
     * No blanks or line breaks are inserted in the output.
     * @param in    An array containing the data bytes to be encoded.
     * @param iLen  Number of bytes to process in <code>in</code>.
     * @return      A character array containing the Base64 encoded data.
     */
    public static char[] encode(byte[] in, int iLen) {
	return encode(in, 0, iLen);
    }

    /**
     * Encodes a byte array into Base64 format.
     * No blanks or line breaks are inserted in the output.
     * @param in    An array containing the data bytes to be encoded.
     * @param iOff  Offset of the first byte in <code>in</code> to be processed.
     * @param iLen  Number of bytes to process in <code>in</code>, starting at <code>iOff</code>.
     * @return      A character array containing the Base64 encoded data.
     */
    public static char[] encode(byte[] in, int iOff, int iLen) {
	int oDataLen = (iLen * 4 + 2) / 3;       // output length without padding
	int oLen = ((iLen + 2) / 3) * 4;         // output length including padding
	char[] out = new char[oLen];
	int ip = iOff;
	int iEnd = iOff + iLen;
	int op = 0;
	while (ip < iEnd) {
	    int i0 = in[ip++] & 0xff;
	    int i1 = ip < iEnd ? in[ip++] & 0xff : 0;
	    int i2 = ip < iEnd ? in[ip++] & 0xff : 0;
	    int o0 = i0 >>> 2;
	    int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
	    int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
	    int o3 = i2 & 0x3F;
	    out[op++] = map1[o0];
	    out[op++] = map1[o1];
	    out[op] = op < oDataLen ? map1[o2] : '=';
	    op++;
	    out[op] = op < oDataLen ? map1[o3] : '=';
	    op++;
	}
	return out;
    }

    /**
    140	* Decodes a string from Base64 format.
    141	* No blanks or line breaks are allowed within the Base64 encoded input data.
    142	* @param s  A Base64 String to be decoded.
    143	* @return   A String containing the decoded data.
    144	* @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
    145	*/
    public static String decodeString(String s) {
	return new String(decode(s));
    }

    /**
     * Decodes a byte array from Base64 format and ignores line separators, tabs and blanks.
     * CR, LF, Tab and Space characters are ignored in the input data.
     * This method is compatible with <code>sun.misc.BASE64Decoder.decodeBuffer(String)</code>.
     * @param s  A Base64 String to be decoded.
     * @return   An array containing the decoded data bytes.
     * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
     */
    public static byte[] decodeLines(String s) {
	char[] buf = new char[s.length()];
	int p = 0;
	for (int ip = 0; ip < s.length(); ip++) {
	    char c = s.charAt(ip);
	    if (c != ' ' && c != '\r' && c != '\n' && c != '\t')
		buf[p++] = c;
	}
	return decode(buf, 0, p);
    }

    /**
     * Decodes a byte array from Base64 format.
     * No blanks or line breaks are allowed within the Base64 encoded input data.
     * @param s  A Base64 String to be decoded.
     * @return   An array containing the decoded data bytes.
     * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
     */
    public static byte[] decode(String s) {
	return decode(s.toCharArray());
    }

    /**
     * Decodes a byte array from Base64 format.
     * No blanks or line breaks are allowed within the Base64 encoded input data.
     * @param in  A character array containing the Base64 encoded data.
     * @return    An array containing the decoded data bytes.
     * @throws    IllegalArgumentException If the input is not valid Base64 encoded data.
     */
    public static byte[] decode(char[] in) {
	return decode(in, 0, in.length);
    }

    /**
     * Decodes a byte array from Base64 format.
     * No blanks or line breaks are allowed within the Base64 encoded input data.
     * @param in    A character array containing the Base64 encoded data.
     * @param iOff  Offset of the first character in <code>in</code> to be processed.
     * @param iLen  Number of characters to process in <code>in</code>, starting at <code>iOff</code>.
     * @return      An array containing the decoded data bytes.
     * @throws      IllegalArgumentException If the input is not valid Base64 encoded data.
     */
    public static byte[] decode(char[] in, int iOff, int iLen) {
	if (iLen % 4 != 0)
	    throw new IllegalArgumentException(
		"Length of Base64 encoded input string is not a multiple of 4.");
	while (iLen > 0 && in[iOff + iLen - 1] == '=') iLen--;
	int oLen = (iLen * 3) / 4;
	byte[] out = new byte[oLen];
	int ip = iOff;
	int iEnd = iOff + iLen;
	int op = 0;
	while (ip < iEnd) {
	    int i0 = in[ip++];
	    int i1 = in[ip++];
	    int i2 = ip < iEnd ? in[ip++] : 'A';
	    int i3 = ip < iEnd ? in[ip++] : 'A';
	    if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
		throw new IllegalArgumentException(
		    "Illegal character in Base64 encoded data.");
	    int b0 = map2[i0];
	    int b1 = map2[i1];
	    int b2 = map2[i2];
	    int b3 = map2[i3];
	    if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
		throw new IllegalArgumentException(
		    "Illegal character in Base64 encoded data.");
	    int o0 = (b0 << 2) | (b1 >>> 4);
	    int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
	    int o2 = ((b2 & 3) << 6) | b3;
	    out[op++] = (byte) o0;
	    if (op < oLen) out[op++] = (byte) o1;
	    if (op < oLen) out[op++] = (byte) o2;
	}
	return out;
    }

    // Dummy constructor.
    private Base64Coder() {
    }
} // end class Base64Coder